There are the difference between StackView of 5.1 and 5.2.0RC1?

I compile and run my source at Qt5.1 and Qt5.2.0RC1. I have working StackView at 5.1 and dont working at 5.2.0RC1.
Dont work "push".
Was made any changes in this item?
An animation of hide Desktop.qml is working, but DialogYesNo.qml dont showing.